The present invention relates to the field of optical communication devices. More specifically, the present invention relates to a receiver optical sub-assembly (ROSA).
In an optical communication system, fiber optic cables are used to transmit and receive large volumes of information at high speeds. In a conventional ROSA, a photodiode chip packed in a coaxial type of transistor outline (TO) can (or package) is typically used to detect optical signals received over a fiber optic cable. Further, the conventional ROSA is widely used for single channel data, i.e. receiving applications with different data rates.
The transmission capacity is increased by multiplexing optical signals of different wavelengths in a single transmission line. One commonly known method of multiplexing is Wavelength Division Multiplexing (WDM). In WDM, optical signals of different wavelengths are multiplexed and transmitted simultaneously, to increase the capacity of fiber optic networks. Networks with a higher capacity can handle a number of services and higher traffic conditions. A combination of two or more optical signals, at different wavelengths, is transmitted over a common optical path. The optical path can be made up of either a single or multimode fiber. Each wavelength is capable of carrying its own independent signal at full speed. However, increasing the transmission capacity of an optical path requires an increase of the component size of a multi-channel ROSA. However, the continuous trend of increasing data transmission speed, with the need for a decrease in component size, makes it challenging to build a multi-channel ROSA by using conventional TO cans.
Further, in order to increase the transmission rate in the optical WDM transmission system, the number of wavelengths to be multiplexed is increased, or the bit rate of the respective wavelengths is made faster. This weakens the demultiplexed optical signals. Thus, there is a need to amplify the weak signals and attain an error-free reproduction. Therefore, a proper design of ROSA, with optical demultiplexing and amplification of electrical signals at high data rates, is required.